The inventive concept relates to photo diodes and methods of manufacturing the same and, more particularly, to avalanche photo diodes and methods of manufacturing the same
Recently, as optical communication systems and image processing systems of high speed and mass capacity have been increasingly demanded, various researches have been conducted for photo detectors essentially used therein.
The photo detectors may detect light reflected or scattered from an object after the light is irradiated to the object. The reflected or scattered light may be condensed by a spherical lens and then be detected in the photo detectors. The light incident on the photo detector may be converted into an electric signal by a photo diode and then be transmitted to a photo receiver through an amplifier. The photo diodes may be categorized into one of a PIN (p-type intrinsic n-type) photo diode and an avalanche photo diode (APD). The PIN photo diode may have no internal gain, such that sensitivity of the PIN photo diode may be poor.
The avalanche photo diode may have more receiving sensitivity than the PIN photo diode. However, the avalanche photo diode may have a complex structure. The avalanche photo diode may have to be designed in planar type for securing reliability thereof. Limitation of the planar structure may cause badness of the avalanche photo diode. For example, edge breakdown may be caused by curvature of an active region in the avalanche photo diode. The edge breakdown may be partially suppressed by a guard ring region surrounding the active region.
However, in a conventional avalanche photo diode, the edge breakdown may not decrease by a dark current caused along a surface of a clad layer between the guard ring region and the active region.